pstorage page size

[ben38]

I try to optmize my code so it can run on the 128k chip. My issue is with pstorage: I have 7 variables (from 4 bytes to 20 bytes) that I store in individual blocks. But it seems that on a page, there is only one block ? So for each block, I need PSTORAGE_FLASH_PAGE_SIZE. if PSTORAGE_FLASH_PAGE_SIZE = 1024, I need 7k to store my 7 variables ?

So I try to reduce PSTORAGE_FLASH_PAGE_SIZE, but I have strange behaviour when I do this. Should it be possible to have PSTORAGE_FLASH_PAGE_SIZE to 20 bytes ?

[Petter Myhre]

PSTORAGE_FLASH_PAGE_SIZE is the actual size of one page in flash, so you shouldn't change that.

You should be able to use a single flash page for this.

It is recommended that the block size is a multiple of the flash word size (4B), so if your largest variable is 20B(5*4B), you can use that as block size. It is also recommended that the block size is a divisor of the flash page size (1024B), that flash page size % block size = 0. This doesn't matter if you use less than 1 page of flash.

I'm assuming you are developing on one of our S110 BLE projects. Have you increased PSTORAGE_MAX_APPLICATIONS to 2? Your application + the device manager. This also increases the number of flash pages available to pstorage to 2 (actually 3, if you include the swap page). One for your application, one for the device manager.

Some variables:

static pstorage_handle_t        m_store_variables_base_handle;
static pstorage_handle_t        m_store_variables_curr_handle;
static int block_number = 0;
static uint8_t block0[4]  __attribute__((aligned(4)));

You must register your application in the pstorage module with something like this:

static void store_variables_init(void)
{
    uint32_t err_code;
    
    pstorage_module_param_t param;

    param.block_size  = 20;
    param.block_count = 7;
    param.cb          = store_variables_cb_handler;

    err_code = pstorage_register(&param, &m_store_variables_base_handle);
    APP_ERROR_CHECK(err_code);
}

You must define the pstorage event handler for your application:

static void store_variables_cb_handler(
                                pstorage_handle_t  * handle,
                                uint8_t              op_code,
                                uint32_t             result,
                                uint8_t            * p_data,
                                uint32_t             data_len)
{
    switch(op_code)
    {
        case PSTORAGE_STORE_OP_CODE:
           if (result == NRF_SUCCESS)
           {
              rdy_for_next = true; // Ready for next store operation
           }
           else
           {
               // Store operation failed. This must be handled
           }
           break;       
    }
}

rdy_for_next is a flag that is checked in the main loop:

// Enter main loop.
for (;;)
{
    if(rdy_for_next)
    {
        store_next_block();
    }
    err_code = sd_app_evt_wait();
    APP_ERROR_CHECK(err_code);
}

The store_next_block() can look like this:

static void store_next_block(void)
{
    rdy_for_next = false;
    uint32_t err_code;

    err_code = pstorage_block_identifier_get(&m_store_variables_base_handle, block_number, &m_store_variables_curr_handle);
    APP_ERROR_CHECK(err_code);
    err_code = pstorage_store(&m_store_variables_curr_handle, block0, 4,0);
    APP_ERROR_CHECK(err_code);
    block_number++;            
}

This should get you started, please add a comment if anything is unclear or if anything requires a better explanation.

[Dibin]

Hi , Can I register for more than 1 page size ??, say i have block size of 16 and I need to reserver 2K memory. So I used count = 128. its returning a 07 error Thanks & Regards, DIbin